Tracking-Based Advertising After Apple’s App Tracking Transparency: Firm-Level Evidence and Policy Implications

We discuss the impact of Apple’s App Tracking Transparency’s (“ATT”) on targeted, online advertising. We overview the empirical results of Aridor, Che, Hollenbeck, Kaiser & McCarthy (2025) that measured the impact of ATT on e-commerce firms. The results point to a large reduction in the efficacy of targeted advertising and subsequently large revenue losses, borne primarily by smaller firms. We discuss the competition policy implications of this by highlighting the potentially ant